This invention relates to a heat-sensitive transfer recording material, more particularly to a novel heat-sensitive transfer recording material containing a magenta dye having excellent spectral characteristic and excellent heat-resistance characteristic.
In the prior art, as the method for obtaining a color hard copy, investigations have been made about color recording techniques by ink jet, electrophotography, heat-sensitive transfer, etc.
Among these, the heat-sensitive transfer system has such advantages as easy operation and maintenance, possibility of miniaturization of the apparatus, reduction of cost, or inexpensive running cost, etc.
The heat-sensitive transfer recording system includes two types of systems. One is the system in which the transfer sheet having a heat-meltable ink layer on a support is heated by a heat-sensitive head to have the above ink transferred by melting onto a transferable sheet, and the other is the thermal diffusion transfer system (including the sublimation transfer system) in which a transfer sheet having an ink layer containing a thermally diffusible dye (including sublimable dye) on a support is heated by a heat-sensitive head to transfer the above thermally diffusible dye onto a transferable sheet.
Of these, the thermal diffusion transfer system is more advantageous for full color recording, because the tone of image can be controlled by varying the amount of the dye transferred depending on the change in thermal energy of the heat-sensitive head.
Whereas, in the heat-sensitive transfer recording of the thermal diffusion transfer system, the dye to be used in the heat-sensitive transfer material is important, and affects greatly the speed of transfer recording, the image quality, the storage stability of image, etc.
Therefore, the dye to be used in the thermal diffusion system as described above is required to be endowed with the properties as mentioned below:
(1) It can be thermally diffused (sublimated) with ease under the heat-sensitive recording conditions (temperature of head, heating time of head); PA1 (2) It should have a preferable hue in color production; PA1 (3) It should not be pyrolyzed at the heating temperature during recording; PA1 (4) It should have good light resistance, heat resistance, humidity resistance and chemical resistance; PA1 (5) It should have a large coefficient of molar light absorption; PA1 (6) It can be easily added to the heat-sensitive transfer material; PA1 (7) It can be easily synthesized; PA1 (8) Further, in addition to these, excellent fixability of image has been demanded.
In the present invention, thermal diffusion refers to diffusion and/or transfer substantially with the dye alone under gas, liquid or solid state depending on the heating energy during heating of the heat-sensitive transfer material, which has substantially the same meaning as the so called "sublimation transfer".
In the prior art, as the magenta dye for heat-sensitive transfer material, there have been disclosed anthraquinone type dyes, azo dyes, azomethine type dyes, etc. in Japanese Unexamined Patent Publications Nos. 79896/1984, 30392/1985, 30394/1985, 253595/1985, 262190/1986, 5992/1988, 205288/1988, 1591/1989, 63194/1989, etc, However, no dye satisfying all of the above-mentioned conditions has not yet been found, and particularly it has been desired to develop a magenta dye in thermal diffusibility, hue, heat resistance, light resistance and a heat-sensitive transfer material by use of said dye.
The present invention has been accomplished on the basis of the state of the art as described above.
Accordingly, the present inventors have made various studies about the dye for heat-sensitive transfer material from the standpoint as described above, and consequently found that the compound of the formula (I) satisfies the conditions mentioned above, and is particularly preferable with excellent hue, to accomplish the present invention on the basis of such finding.